Madison Hazmat Scenes Tied to Cyanide Poisoning Plot; Two Arrested in Multi-Agency Investigation

A chilling cyanide poisoning plot has been uncovered in Madison following a multi-agency investigation involving hazmat teams, multiple search warrants, and two arrests now tied to attempted homicide charges.

The Wisconsin Department of Justice’s Division of Criminal Investigation (DCI) confirmed that three separate hazardous materials scenes—on West Skyline Drive, North Spooner Street, and Schroeder Road—are linked to a coordinated effort to poison two women. The suspects, Paul Van Duyne and Andrea Whitaker, now face serious felony charges.

According to Dane County Assistant District Attorney William Brown, Van Duyne attempted to murder two former romantic partners by lacing their water bottles with cyanide. One of the victims was targeted twice in a Costco parking lot in Middleton, where Van Duyne allegedly broke into her vehicle and planted the poison. In a separate Rock County incident, another woman was hospitalized after her gym water bottle was tampered with. A powdery substance was found in her car.

Van Duyne, 53, was arrested Sunday night at the Rock County woman’s home. Following his arrest, prosecutors say he called Whitaker—his current partner—and instructed her to remove incriminating items from his home, including his computer and suspected chemical agents.

Whitaker, who has a background in pharmacology, was later arrested and charged with harboring or aiding a felon. Her defense attorney claims she may have been unaware of the criminal nature of her actions. But prosecutors revealed damning evidence, including Whitaker’s search history (“cyanide lethal dose” and “Does potassium cyanide powder go bad?”) and message exchanges where the pair allegedly discussed various poisons and their methods of use.

Investigators executed search warrants across several locations, sparking emergency responses and a significant police and hazmat presence. Spooner Street was closed for several hours Tuesday as officers and hazmat crews worked near Van Hise Avenue. Madison Fire Department Hazardous Incident Team, the Wisconsin National Guard, Middleton Police, and the DCI were all involved.

District 5 Alder Regina Vidaver had emailed residents early Tuesday, warning of police and hazmat activity in the area. Rachel Herbsman, a local resident, described seeing officers in hazmat suits roping off the street. Gracie Harmann called the scene “really weird,” while others said it felt “sad” and “concerning” given the neighborhood’s quiet nature. Timothy Coenen said the heavy response made it all the more alarming.

Authorities initially declined to release details, but Madison Fire PIO Cynthia Schuster later confirmed the Tuesday response was tied to Monday’s activity on West Skyline Drive and South Highlands Avenue.

Van Duyne is charged with attempted homicide and stalking and is being held in the Dane County Jail. Whitaker’s cash bail was set at $750,000 due to the severity of the alleged crimes. Both are scheduled to return to court the Friday following the Juneteenth holiday.

DCI officials maintain there is no ongoing threat to the public, but have asked residents to avoid the affected areas as investigations continue.

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